What Causes Recurrent Bumps On Head After Injury?

I am 76, have an artificial heart valve, take warfarin, also have high blood pressure, high cholesterol, diabetes. But am kept in fairly good health by specialists. Last Thursday I fell, hit the back of my head, a big lump formed, and I went to the ER because of taking the warfarin. Blood work done, EKG done, CT scan with contrast was done, all checked out fine. Used ice. Bump went away. Stayed in hospital 23 hours for observation. By the time I went home, the golf sized bump was gone. The black and blue mark was gone. Yesterday, I noticed a bump once again at the same place, but is not black and blue. No symptoms that I can tell. Using ice. Don't want to go back to the ER unless absolutely necessary. Is a bump coming back unusual?